Color diffusion transfer photography method using azo dye image forming substances which give azo dyes different from image forming compounds themselves in diffusibility as a result of development under basic conditions has hitherto been well known. As dye releasing compounds, the compounds described in U.S. Pat. No. 3,928,312 are known.
However, the dye releasing efficiency of these dye releasing compounds is not always high, so that the compounds have the problem that the transfer density is not sufficiently obtained.
On the other hand, conventional color diffusion transfer film units are used for indoor or outdoor picture taking in many cases, and processed through a wide temperature range. Hence, the high treating temperature dependency of transfer density introduces a serious problem.
These tendencies are particularly noticeable in alkali treatment at low temperatures. Also in this sense, a technique for improving the transfer density and the treating temperature dependency of transfer density has been desired.
Further, as a means for improving the transfer density with additives, a method is described in JP-B-4-13701 (the term "JP-B" as used herein means an "examined Japanese patent publication") in which a sulfonamide compound is added as a methanol solution to a layer containing a dye providing substance, followed by processing at a high temperature in a dried film system.
However, addition of the compound disclosed in the above-described patent did not show improvements in transfer density and treating temperature dependency.